A new male contraceptive is being hailed a “game-changer” as it’s been found to temporarily pause fertility in mice without affecting their long-term sperm production. Mice given the treatment became infertile but maintained normal mating behavior, and by the next day were fully fertile again.
The male contraceptive works by inhibiting soluble adenylyl cyclase (sAC) with a single dose of medication. This effectively paralyzes sperm as sAC is essential for its maturation and motility.
Fully fertile male mice were either injected with or given an oral dose of an sAC inhibitor that temporarily rendered them infertile within 30 minutes. This was because their sperm could no longer make the journey from a female’s vagina to its uterus.
In humans, the epic journey these microscopic gametes must traverse is even more complex as sperm have to cross the barrier of the cervix before they can make it into the uterus. The researchers say that in the context of their temporary treatment, this would leave immotile sperm stuck in the vagina where they’d soon perish as it quickly becomes acidic after copulation.
It has so far only been tested in mice as a full-body model, but was also found to have a similar impact on human sperm in test tube trials. While it will require more testing before it can be rolled out as human medicine, if effective it could provide the first birth control of its kind that can be taken only when the situation calls for it, potentially making the lives of both parties involved a little easier.
The treatment could be ground-breaking in two respects, first in providing a potential non-hormonal form of male contraception and second in creating a treatment that is temporary and can be taken on-demand (it also doesn't require heating testicles with magnets, which most people would probably consider a plus). Many existing contraceptives for women and those being studied for men involve long-term treatment which comes with long-term effects.
In the short term, the researchers say there’s less to worry about. Side effects brought on by sAC inhibitors usually require chronic use to come into effect, including raised pressure in the eye leading to glaucoma, and kidney stones.
“These studies provide a framework for developing an on demand male contraceptive and define sAC inhibitors as lead compounds for on-demand, non-hormonal, male contraceptives,” concluded the study authors. “This innovative, on-demand, non-hormonal strategy represents a previously untested concept in contraception, which has the potential to provide equity between the sexes and, like the advent of oral birth control for women, revolutionize family planning.”
The study was published in Nature Communications.